The warrant came two days after FBI director James Comey revealed the existence of the emails, which law-enforcement sources said were linked to Weiner's estranged wife, top Clinton aide Huma Abedin.

The FBI already had a warrant to search Weiner's laptop, but that only applied to evidence of his allegedly illicit communications with an underage girl.

Comey's disclosure of the emails ignited fierce criticism, particularly from Clinton, who called the move an "unprecedented" departure from FBI policy.

On Sunday, Democratic Senate Minority Leader Harry Reid scolded Comey as well, saying in a letter that he "demonstrated a disturbing double standard for the treatment of sensitive information, with what appears to be clear intent to aid one political party over another."

Reid added that his office determined that Comey may have violated the Hatch Act, which bars government officials from using their authority to influence elections.

The FBI did not immediately respond to requests for comment on the Reid letter.